Function json_lex_string

src/common/jsonapi.c:679–885

* The next token in the input stream is known to be a string; lex it. */

 * The next token in the input stream is known to be a string; lex it.
 */
static inline JsonParseErrorType
json_lex_string(JsonLexContext *lex)
{
	char	   *s;
	int			len;
	int			hi_surrogate = -1;

	if (lex->strval != NULL)
		resetStringInfo(lex->strval);

	Assert(lex->input_length > 0);
	s = lex->token_start;
	len = lex->token_start - lex->input;
	for (;;)
	{
		s++;
		len++;
		/* Premature end of the string. */
		if (len >= lex->input_length)
		{
			lex->token_terminator = s;
			return JSON_INVALID_TOKEN;
		}
		else if (*s == '"')
			break;
		else if ((unsigned char) *s < 32)
		{
			/* Per RFC4627, these characters MUST be escaped. */
			/* Since *s isn't printable, exclude it from the context string */
			lex->token_terminator = s;
			return JSON_ESCAPING_REQUIRED;
		}
		else if (*s == '\\')
		{
			/* OK, we have an escape character. */
			s++;
			len++;
			if (len >= lex->input_length)
			{
				lex->token_terminator = s;
				return JSON_INVALID_TOKEN;
			}
			else if (*s == 'u')
			{
				int			i;
				int			ch = 0;

				for (i = 1; i <= 4; i++)
				{
					s++;
					len++;
					if (len >= lex->input_length)
					{
						lex->token_terminator = s;
						return JSON_INVALID_TOKEN;
					}
					else if (*s >= '0' && *s <= '9')
						ch = (ch * 16) + (*s - '0');